You can use the default groups that are created at the level of team project collections to manage the users who will have access to projects that are hosted in a collection. As an alternative, you can create custom groups at the collection level and grant those groups specific permissions to better align with your business needs. Collection-level groups are created directly within the team project collection, and they have permissions that are not specific to any one team project within the collection. This is in contrast to team project groups, which are associated with a specific project. Collection-level groups can be assigned permissions to perform tasks throughout the collection itself, such as creating projects or administering users. They can also be assigned to projects and given project-specific permissions, such as permission to start a build or delete a project.